Boring cutter



5, 1952 E. J. KAISER 2,605,655

BORING CUTTER Filed Sept. 21, L948 IN VEN TOR. w Erwin J. K0168! Patented Aug. 5, 1952 BORING CUTTER Erwin J.

Kaiser, Fond du Lac, Wis., assignor to -Giddings & Lewis Machine Tool Company, g Fond du Lac, Wis., a company of Wisconsin Application September 21, 1948, Serial No. 50,315

The present invention pertains generally to cutting tools and more particula'rlyto a boring cutter having a cutting tip of cemented carbide or the like. The use of high-speed cutting tips of carbide material frequently presents serious practical difliculties with regard to their mounting. One widely accepted expedient involves brazing the cutting tip to a block or holder of steel. Due to the differential expansion rate between the steel and the material in the tip, there is a tendency for excessive temperature stresses 1 Claim. (01. 77-58) to occur in the tool, thereby limiting its life and Y also its effectiveness. Another mounting expedient which is particularly well suited for use in large tool sizes involves clamping the cutting tip to the holder by means of mechanical pressure. Arrangements of this type overcome the disadvantages inherent in brazing the tips to their holders but are not always satisfactory in practice due, for example, to the application of high localized clamping stresses which are apt to result in tool breakage.-

One object of the invention ,is to provide a boring cutter having a novel and, improved arrangement for mechanically holding a high-speed cutting tip of carbide or the like.

Another object is to provide acutter of the character set forth and wherein the bladecan be changed quickly so as to minimize the downtime of the machine.

A further object is to provide a cutter of the above type and which will be simple, rugged, and

susceptible of economical manufacture.

Other objects and advantages will become apparent as the following detailed description proceeds, taken in connection with the accompanying drawings wherein: 1

Figure l is a side elevation of an illustrative boring bar having a pair of cutters embodying the present invention.

Fig. 2 is an enlarged perspective view of an illustrative cutter embodying the invention.

Fig. 3 is a front elevation of the cutter shown in Fig. 2. 5

Figs. 4 to.6 are respectively left-hand, righthand, and bottom end views of the cutter in Fig.3.

Fig. '7 is an enlarged transverse sectional view through the cutter of Fig. 3, such view 'being taken in the plane of the line 1-1.

Fig. 8 is an enlarged side view detailing the clamping plunger per se.

Fig. 8A is a transverse sectional view through the plunger of Fig. 8, taken in the plane of the line 8A8A.

Fig. 9 is a plan view of Fig. 8.

,While the invention is susceptible of various modifications and alternate constructions, a preferred embodiment has been shown in the drawings and will be herein described in considerable detail. It should be understood, however, that there is no intention to limit the inventhe plunger shown in tion to the specific form disclosed but, on the contrary, the intention is to cover all modifications, and alternative constructions falling within the spirit and scope of the invention as expressed in r the appended claim.

Referring more specifically to the drawings,

the invention is-there shown embodied in an illustrative boring cutter l0 comprising a generally rectangular cutter block H and a hardened cutting blade l2 of cemented carbide or the like. In the present instance, the latter has a substantially uniform trapezoidal cross section throughoutits length, being formed with mutually inclined lateral edge surfaces i4. On the end away from the blade I2, the block I l is fashioned with two sets of wedge bearing surfaces l5 separated by a relatively wide U-shaped notch 16.

In practice, a pair of the cutters [0 may be operatively supported ina boring bar lB"(Fig. 1) having a transverse tool slot I9. The latter is of appropriate size to slidably receive the cutters l0 which are mounted in end-to-end relation therein with their bearing surfaces I5 facing inwardly. To permit radial adjustment of the cutters 10, the boring barl8 may be formed with a diametri cal bore (not shown) intersecting the slot l9 at degrees and housing an expansion wedge (not shown) together with a micrometer adjustingscrew 22. The wedge has inclined'surfaces which cooperate with the surfaces [5 to expand the cutter radially of the bar [8. Eccentric clamping screws 24 may also be used with the bar lBto secure the cutters in place'after proper adjustments have been made.

To receive the blade l2, the cutter (Figs. 2, 3 and '7) is formed with a'relatively wide diagonal slot 25 in one of its larger 'side faces 25, such slotstarting adjacentthe central portion of the face'ifi and terminating at the tool supporting end and an adjacent lateral edge face of the block, or in other words, at one of the corners thereof located away from the wedge bearing surfaces I5. Side walls 28 of the slot 25 are undercut at an angle sub stantially equal to the inclination of the blade edges I4, making an acute angle with the face 26 and also with slot floor 29 which is generally block i l parallel to the face 25. The slot 25 is suitably dimensioned to accommodate the blade i2 in telescoping relation with a sort of sliding dovetail fit, permitting the blade to move longitudinally thereof but constraining it against movement in any other direction.

Provision is made for adjustably clamping the blade 52' againstflongitudinal' movement Within the slot 25 without the use of wedge members and without applying undue concentrations of localized clamping stress to the blade.

This is accomplished in the present instance by theuse I of a clamping plunger 30 (Figs. 7 to 9) slidably housed within a transverse beret-l disposedat about 90 degrees to the longitudinaliaxi's of the slot 25 and intersected along a portion of its length by the plane of the; slot floor; 2q as best shown in Figures 4 and 7 of the accompany- 7 ing drawings. The plunger 3%] comprises-a generally cylindrical body having a squared-off inner end 32 and an angular outer end 3 Running longitudinally of the plunger 36 from its inner end-32 and terminatingatan undercut shoulder 35 is a relatively wide fiat 3E. The latter, being approximately coplanar with the slot floor' 28 when the plunger is installed in the bore '31, underlies the blade I 2 transversely. Bythe same token, theshoulder- 35, being undercut at about the" sameangle as'the side walls 23 01" the slot, is conveniently arranged to engagethe adjacent blade edge I l'with which it'iscomplementary;

Operativelyassociated with the clampingplun ger 30 for actuating the same is a drawscrew 38 having a threaded" shank 39. which engages a tapped hole' ll) running longitudinally of the pluner; Thezheadl of the screw 33 is located within" a counterbore t! in the block H arranged in substantial alinement with the bore 3i. Interposed between the latter and" the. ccunterbore l-l. is an annular shoulder-42 having an axial hole 44' which connects the bore St and the counterbore Hand is of slightlygreater'diameter than the screw shank 39; With such arrangement,'theshoulder l2 constitutes a firm anchorage for the head of the screw 38. Thus tightening of the latter will tend to draw the plunger 39 towardthe shoulder dz. and'at the same time the undercut'shoulder 35. of. the plunger will accost the adjacent edge i l of the blade l2. This, in turn, will result in urging the, blade i2 and its, opposite edge laterally and into tight frictional engagement with the remote side wall 28 ofxthe slot25. v

Locatediadjacent the rearward end of the slot 25.; is an. adjustable: stop means for defining the' positionlof the blade in the slot'prior to clamping theformer', such position being one wherein the cutting edge of the blade overhangs the tool supporting end of the block by a relatively slight margin.

blade I 2. The screw 45 is mounted in a tapped hole 49 which starts at the right hand edge of the block ll (Figs. 3 and 5) and intersects the slot 25, terminating in the vicinity of the longitudinal axis of the latter. The hole 49 is preferably given the necessary angular relation to such axis to obtain line bearing contact between the conical tip 46 and the end 48 of the blade 12.

It can now be appreciated by those skilled in. the art that the blade mountingarrangement just described possesses a number of advantages. Not

In the present instance, such means comprises a screw 45 having a conical tip 46 adapted to bear against squared end 48 of the,

convenient location of the screw 33 renders the same readily accessible from the outermost end ofith e block H} without moving the cutter I!) or -otherwise-disturbing the setup of the boring tool in which the same may be used. This tends to minimize the downtime of the machine incident to changing blades. The foregoing mounting arrangement also avoids undue temperature stresses during cutting operations because the blade I2 is left'freeto'expand'or contract relative to the block i ""Elconomyof manufacture. is:

assured by reason of the simplicityiof the component parts.

I claim as-my invention: A boring cutter comprising the combination of'a' generally rectangular cutter block havinga tool supporting end and a: substantially diagonal slot in one side face thereof terminating at said tool supporting end and an adjacent lateral. edge face of said block, each lateral side-wall of said slot beingflundercut and thefloor of said slot being parallel to said side face of "said block, said block" also having a bore and an alined counter,- bo're running. perpendicular to the longitudinal of the slot but being parallel with the floor thereof; thebore being intersected along'a portion of its length by the plane of the slot. floor, the counterb'ore being formed in. said tool sup.-

porting end of said block, an annular shoulder interposed between the bore and thecounterbore, a cutter blade telescopically housed within the diagonal slot with its cutting edge proj ectingfrom said tool supporting end and from said lateral I edge face by a relatively slight margimsaid cutter blade being of trapezoidal cross section, a clamping plunger slidably disposed within said bore and having a relatively wide flat coplanar with said'slot floor andunderlying the blade trans:-' versely when said plunger is installed in said bore, said fiat terminating at its inner end in an upstanding; undercut shoulder arranged in complemental abutting engagement with the lateral edge 'ofsaid blade remote from said annular shoulder'for the application of clamping'force'to' said blade parallel to the floor of said slot, and a drawscrew threaded into said plunger and hav inga head disposed in'bearing'engagement with said annular shoulder, said drawscrew head being freely accessible from said. toolsupporting' end of said cutter block.

1 ERWIN J. KAISER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,746,381 Davis Febpll, 1930' 2 0761563- Miller Apr. 13, 1937 2,197,162

Smith Apr. 16; 1940 

